Results of the "Scan the Pyramids" project have been published today. They show a large void above the Grand Gallery. This void is about the size as the Grand Gallery in cross section and has a minimum length of 30m. There is no information about the orientation of this void in relation to the Grand Gallery or how far above it is. This publication is rather skimpy and I'm sure will be fleshed out later with some graphics so we can better see hos this looks in relation to the known structures in the Great Pyramid.
https://www.nature.com/nature/journal/vaap/ncurrent/full/nature24647.html

I saw an article on this...very interesting indeed. I saw a cross section graphic that showed the void was near one of the King's Chamber shafts, but I don't suppose the void would be accessible in that way.

I know they sent those little robots up the Queen's Chamber shafts...did they ever do this with the King's Chamber shafts?

Yes, they did the King's chamber shafts as well, and nothing found except that both bend a some point along their course.

On this void there are dissenting voices already, chief among them being Zahi Hawass who said that it is not a void but a change in construction materials. The Scan Pyramids team refuted this in a teleconference with Hawass before publication. Mark Lehner has proposed that this void serves the same function for the Grand Gallery as the relieving chambers do for the King's Chamber. I would note that nobody has ever previously stated that the Grand Gallery would need a relieving chamber. It's so strongly corbelled that I cannot see that it needs some form of protection above it. This void does not fit in with Houdin's internal ramp theory either as it is not around the inner surface of the pyramid. Though of course it may well be a construction ramp, just one not imagined before. I'm sure we will be well entertained by all manner of theories for some time to come....

On this void there are dissenting voices already, chief among them being Zahi Hawass who said that it is not a void but a change in construction materials. The Scan Pyramids team refuted this in a teleconference with Hawass before publication.

I have heard suggestions previously that sand was used in some areas of the pyramid to "fill in" gaps around blocks. However in this case, that would seem to be a lot of sand.

A lot of sand that over time would gradually work it's way downwards and into other voids, and so possibly cause an internal collapse of the pyramid above a void this big if it were filled with sand.

I wait to see if this void is sloped, as Lehner suggests, or horizontal. I think a sloped void could be a form of structure outside of a "treasure chamber", while a horizontal void will be somewhat more interesting....

Dr. Mostafa Waziri, Secretary-General of the Supreme Council of Antiquities denies all reports published in some international newspapers and online news agencies that French researchers are fabricating an exploration robot that is set to reveal the secrets of mystery chambers inside the Great Pyramid of Giza.

He asserted that the ministry of Antiquities and the Permanent Committee of the Ancient Egyptian Antiquities didn’t give any approval for the production or usage of an exploration robot inside the Great Pyramid for the French researchers or any local or global entities.Even, he continues, there is not any agency or organization or association or Institute or anybody have asked for such request.

Dr. Waziri explains that the using of this technology is based on many researches and scientific studies and approval of the ministry and not based on a personal opinion in order to guarantee the protection and preservation of the monuments.

He also asked the media to be more cautious before publishing the news and the Ministry of Antiquities is always opening its doors to media to provide them with any required information.

... the death Pharaoh must first pass through the "gates to heaven" and sit down on the "throne of iron" before he can reach the northern sky, the "dwelling place of Pharaoh after his earthly death".

The ways to the "northern sky" may already be known: Two narrow shafts that lead from the middle of the pyramid to the outer wall and are aligned to constellations. Two similar shafts, however, end at gates inside. What's behind it is unexplored so far. One of these two shafts could lead to the new cavity. ...

... Giulio Magli, Director of the Department of Mathematics and Professor of Archaeoastronomy at the Politecnico di Milano, has formulated one of the first hypotheses of interpretation.

"Cheop's Pyramid, built around 2550 BC, is one of the largest and most complex monuments in the history of architecture. Its internal rooms are accessible through narrow tunnels, one of which, before arriving at the funerary chamber, widens and rises suddenly forming the so-called Great Gallery. The newly discovered room is over this gallery, but does not have a practical function of "relieving weight " from it, because the roof of the gallery itself was already built with a corbelled technique for this very reason." ...

... "There is a possible interpretation, which is in good agreement with what we know about the Egyptian funerary religion as witnessed in the Pyramids Texts. In these texts it is said that the pharaoh, before reaching the stars of the north, will have to pass the "gates of the sky" and sit on his "throne of iron".

Within the Pyramid there are four narrow shafts, the width of a handkerchief, directed to the stars. The pharaoh's afterlife was in fact, according to the Texts, in the sky, and in particular among the stars of the north, like the Big Dipper and Draco. Two of the four channels open onto the facades of the monument, while the other two run into small doors. One of the two doors, the south one, has been explored several times without results, while the north one is still sealed.

These doors are with all probabilities representative of the "gates of the sky" and the north one could well lead into the newly discovered room. The room may contain, at its upper end and exactly under the apex of the great pyramid, an object needed by Cheops after crossing the doors: the "iron throne" mentioned in the Pyramid Texts. ...